The invention relates to spring-mass systems, particularly those used to support transducers in rotating record disk storage apparatus.
The natural frequency of a mechanical oscillator designed as spring-mass system is determined, by the mass of a movable body and the constants of the spring elements. The resonance frequency of such a mechanical oscillator is critical in the construction of machines and devices equipped with such oscillation systems. It is desired to avoid synchronous vibrations of the machine or adjacent components and component groups, whose components exhibit different resonance frequencies. However, the success of such avoidance can suffer if during machine operation the natural frequency of the machine changes. It is a common belief that all known spring-mass systems have a constant resonance frequency and that it cannot be balanced without altering the oscillating mass or changing the spring or springs. Such a situation exists in record disk storage apparatus, particularly in the transducer support mechanism.
A structure having a pair of electromagnetic coils on both sides of, and symmetrical to, a movable body is known, e.g. as used in a measuring device for seismic and gravitation measurings in accordance with U.S. Pat. No. 2,776,560. The movable body is an oscillator and analogously represents a measured value; however, it is not part of a spring mass system but is guided in the air gap of an electromagnetic field. The coil pairs have an additive effect for determining the resetting forces corresponding to the respective setting forces, and for generating the analog signals representing the setting paths.
On the other hand, dividing an electromagnetic working coil into coil halves, as such, is also known. Such coil halves can be effective either in an aiding or opposing directions. Such coil halves can center a movable element and stabilize it in a central position. However, depending on the direction and height of the deviation, such coil halves can still receive different current intensities for independent positioning correction.